The present invention relates to the monitoring of capillary blood flow in a woman's cervix and vagina for the diagnosis of various physiological conditions.
The ability to monitor capillary blood flow in a woman's cervix provides the potential to obtain important physiological data for the diagnosis of a wide range of conditions of concern both in obstetrical and gynecological practice. Even though the status of the pelvic flow has great medical significance, little research has been done in this area. This is primarily due to the absence of adequate, convenient non-invasive instrumentation to collect and reduce capillary blood flow data so that normal and abnormal circumstances can be identified.
During pregnancy, adequate uterine artery blood flow is the most important single factor in fetal growth and development. In situations where it is markedly compromised as the consequence of overt maternal cardiovascular disease, the fetus may be undergrown, or even die. In the human patient, it is not possible to obtain an accurate measurement of uterine blood flow directly with non-invasive techniques. However, the uterine artery supplies not only the corpus of the uterus, but also the cervix uteri and the vagina through its vaginal branches. Hence, it is possible to determine to a large extent, the status of uterine artery blood flow by evaluation of cervical and vaginal capillary blood flow.
The evaluation of uterine artery blood flow is of importance during gestation to determine if it is adequate. It may be compromised by maternal cardiovascular disease, diabetes mellitus, toxemia of pregnancy and other diseases. If the uterine artery flow is diminished, maternal treatment would be reevaluated to find a more efficacious treatment. In circumstances where it is compromised to the point where intact fetal survival is threatened, the gestation would be terminated to save the fetus from irreversible damage or death.
During labor and in the late antepartum period uterine contractions constitute an additional stress to the fetus, since each contraction decreases blood flow to the placenta. Hence, it is doubly important at these times to measure uterine blood flow. Another concern during labor is material hypotension as a consequence of maternal position and/or conduction anesthesia. The presence of hypotension adds an additional fetal hazard.
The woman's uterus and vagina are both supplied with blood by the uterine artery. Capillary blood flow in the cervix and vagina is related directly to uterine artery flow. The ability to monitor continuously such capillary flow provides the potential for acquiring data of clinical significance e.g., uteroplacental insufficiency, the effect of uterine contraction on uterine blood flow.
Maternal hypotension can result from blockage of the veins returning blood to the heart from the pelvis as a result of pressure exerted by the uterus. This is apt to occur especially in the case of the patient with conduction anesthesia, inasmuch as her blood tends to pool in the pelvis. The reduced input of blood to the heart as a consequence of these conditions leads to reduced cardiac output and consequent hypotension. This condition is potentially dangerous to the fetus due to the consequent reduction in the flow of oxygenated blood to the uterus.